Ultramarine Europe provides analyses to support FEED, Basic & Detail design in the following areas:
- Pre-service analyses and decommissioning of fixed and floating structures
- Mooring analyses of floating structures
- Pipelying analyses
- Floating wind turbine analyses
- Special Projects
In each of the above fields, our approach is the same as the one we used as software developers i.e. “Think Global”.
A marine operation often involves several vessels that interact with each others, and each vessel may be made of several parts. The regular approach is to study each part independently and to apply the results from each part to the next one in terms of loads, offsets etc… We strongly believe that this is not satisfying, both technically and intellectually, and that the global approach toward the simulation, which includes all the elements involved in the operation, lowers the level of conservatism and reflects the reality more accurately.
T&I covers different aspects of pre-service for fixed and floating structures.
- Transportation & Towing
- Lift & Lowering
- Deck Mating
- Float-off, float-on
All these operations require information concerning stability, longitudinal strength, motion and structural integrity. We provide this information in a global way, no matter the complexity of the configuration.
Depending on the subject, studies are done in the frequency domain or in the time domain. Often, both are needed if not required.
Spectral approach during transportation allows to analyse the structures by solving the stiffness matrix directly from the hydrodynamic behavior of the vessel. When the regular approach combines extreme load cases following an arbitrary procedure, we remove any conservatism from the results.
Over the years we developed tools to automate most of the tasks involved in T&I studies.
As a result we can check the strength of a jacket structure during transportation, launch and upending in a single analysis by defining code checks over the whole sequence.
This has a major impact on the time needed to design the structure.
Among all the tasks, deck mating analysis is an interesting one. This is in fact an impact problem with its own specificities (ultra short time increment, large range of connection stiffnesses) involving a lot of similar tasks for which automated procedures can drastically reduce the time needed to complete.
The purpose of mooring analysis is to design a mooring system (pattern and line sizes) that produce connector loads and motions that are acceptable under the action of specified environments. Sometimes this is part of a larger study such as lifting a structure so here the efficiency of the operation is part of the objective of the analysis.
Most of the time, the analysis is done in the time domain in order to account for the non-linearities of the system, but the frequency domain approach allows to identify the worst cases among all environments (often thousands). Then time domain is used on the cases of interest.
One particular aspect of the mooring study is the breaking of a line. Running the simulation in the time domain allows to get information during the transient phase, in terms of offsets and loads and to design the lines accordingly.
The key points are the tension of the pipe, shape and angle of the stinger and the height of the rollers.
Most of the time, only static analysis is needed, but dynamic ones provide more information in terms of deflections, loads on the rollers and dynamic behavior of the stinger.
The regular approach is to study separately barge motion and pipe response. We do not believe the popular approach of uncoupling the motion of the barge from the pipe response is satisfying, because the pipe is like a stiff mooring line and affects the motion of the barge, particularly in surge and sway. In our models, the barge, stinger and pipe are considered as a whole system and all contributions are accounted for.
This setup is particularly adapted for stinger structural check. It is just derived from the history of all loads applied to it (rollers, environment, acceleration of the barge etc…).
The main difference between the dynamic response of a conventional floating structure and a floating wind turbine is the influence of additional effects on the behavior of the floater, due to aerodynamic loads on the blades and active blades pitch control.
In order to consider the gyroscopic effect of the wind loading, new tools are needed.
Study of floating offshore wind turbines is done now with MOSES including additional module OpenWindPower.
The package interoperates with third party aeroelastic solvers to complete a hydrodynamic and structural analysis of the floating foundation. Floater can be designed structurally by carefully synchronizing the history of water surface elevation, turbine load, mooring line loads and floater motion. And as usual with MOSES, the process is fully integrated in the software.
The time for designing the floater is reduced and take advantage of the MOSES language to automate the computation of the loops needed in the Load Case Tables.
Ultramarine Europe and partners have developed an expertize in dealing with such problems over the past months.
We are a versatile company with the knowledge, experience and problem-solving ability to tackle any challenge efficiently and professionally.